The objectives of this proposal are to elucidate the mechanisms by which gonadal steroids and hypothalamic peptides exert their actions on adenohypophyseal cells. A monolayer culture system of rat adenohypophyseal cells established in this laboratory (16) will be used in order to allow the study of the direct action of steroid and peptide hormones on the adenohypophyseal cells without the influence of endogenous hormones. The following selected areas will be studied: 1. The effects of sex steroids and their metabolites on the release and synthesis of gonadotropins will be examined both quantitatively by radioimmunoassay and qualitatively by fractionation with gel filtration chromatography and polyacrylamide gel electrophoresis before radioimmunoassay. 2. The interaction of steroids and LHRH on gonadotropin synthesis and release will be examined at the following molecular levels including the effects of sex steroids on: a. LHRH-receptor and LHRH-binding; b. LHRH-sensitive-adenylate cyclase system; c. the degradation of LHRH. 3. Studies will also be made to establish clones of LH- or FSH-producing cells for future studies of LHRH action in cloned cell populations.